Update XML classes to use OVERRIDE / FINAL when needed

Source/core/xml/XPathVariableReference.h

Index: Source/core/xml/XPathVariableReference.h
diff --git a/Source/core/xml/XPathVariableReference.h b/Source/core/xml/XPathVariableReference.h
index e494a46721591c4e5e776bf21bdbcfe215c46048..a53599ed70cc32771dffdc268e203363f54aa390 100644
--- a/Source/core/xml/XPathVariableReference.h
+++ b/Source/core/xml/XPathVariableReference.h
@@ -33,12 +33,12 @@ namespace WebCore {
     namespace XPath {
 
         // Variable references are not used with XPathEvaluator.
-        class VariableReference : public Expression {
+        class VariableReference FINAL : public Expression {
         public:
             explicit VariableReference(const String& name);
         private:
-            virtual Value evaluate() const;
-            virtual Value::Type resultType() const { ASSERT_NOT_REACHED(); return Value::NumberValue; }
+            virtual Value evaluate() const OVERRIDE;
+            virtual Value::Type resultType() const OVERRIDE { ASSERT_NOT_REACHED(); return Value::NumberValue; }
             String m_name;
         };